Miniature fluorescent and/or glow lamp



P. M A T d .W o v AL G R 3 i D m .OA A m 1 EE i2, w A o. E, m 2 W at.. R E v f m o w M E D m w u C m n F. E R U T A I N T.. M E w 9 mw 1 /Sv om, n a J BY www A TTORNEY- Patented Jan. 8, 1946 Chalmers Morehead, East Orange, N. J., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 20, 1943, Serial No. 514,960

11 Claims.

This invention relates to miniature negativeglow lamps, and, more particularly, those in which the enclosing envelope is coated with fluorescent material in order to adapt them to functionas small decorative lamps.

The primary object of my invention, generally considered, is to produce a miniature lamp of the negative-glow, gaseous-conduction type in which the envelope may be coated with fluorescent ma terial to give it a desired color to adapt it for decorative purposes.

Another object of my invention is to provide a small Christmas tree lamp adapted for the production of a more desirable color effect than incandescent filament lamps, while running cooler and thereby consuming a correspondinglysmaller amount of energy.

A further object of my invention is to produce a small low-power self-starting ultraviolet, or iluorescent lamp to produce white or colored light for decorative or other purposes, or one to be used as a source of ultraviolet in the 3600 A. U. region.

A still further object of my invention is t produce a miniature low-power, self-starting,

fluorescent and/or glow vlamp in which the source of radiation is a pair of coiled coil lilaments coated with electron-emission material, with adjacent ends connected and supported, diverging from one another, and having their remote ends secured to supporting leads, whereby when energized a glow discharge occursbetween the remote end portions, activating a suitable phosphor, if disposed on the lamp envelope, for the production of light of the desired color.

' Other objects and advantages of the invention,

relatin'gto'the particular arrangement and construction of the various parts, will become apparent as the `r lescriptiori proceeds.

Referring 'tothe drawing illustrating preferred embodiments of my yinvention to scale; Fig. lis an elevational view, shown full size in the original drawing, of a iluorescent lamp ,em-

`bodying my invention.

f Fig. 2 is an enlarged axial sectional view of the lamp of Fig. 1, showing the enclosed mount in face elevation.

Fig. 3 is an edge elevational view-of the mount shown in Fig. 2.

Fig. 4 is a perspective view of a mount of another embodiment of my invention.

Fig. 5 is a, view corresponding to Fig. 4, but illustrating a mount of still another embodiment of my invention.

Fig. Gis a circuit diagram of lamps embody' ing my invention in series with a ballast lamp. Fig. 7 is a circuit' diagram of a lamp embodying my invention, in series with the filaments of a plurality of radio tubes.

Referring to the drawing in detail, and rst considering the embodiment of my invention i1- lustrated in Figs. 1, 2, and 3, there is shown a lamp II particularly adapted for operation with seven others and a suitable ballast resistor in series in a string, as for Christmas tree decoraytion on a domestic volt circuit. Said lamp comprises an envelope l2, which may be formed of ordinary soft glass, Corex, `or other ultraviolet transmitting glass and correspond in sizewith' such usually employed for Christmas tree lamps, said envelope enclosing a mount I3 which may be sealed therein by the well-known method termed butt sealingfor, if not coated, as described and claimed in the Carpenter Patent No. 2,235,515, dated March 18, 1941.

The mount I3 may 'be very simply constructed of a glass bead I4 through which supporting leads I5 and I6 of dumet or other suitable material 4 extend, and to the inner ends of which are connected, as by spot welding, the ends oi a filament Il. The lament Il, in the present embodiment,

comprises two sections I8 and I9, each conslst.

ing of a coiled coil filament oi' tungsten, the adjacent endsy of said sections being connected by a straight portion, which is in turnconnected to a center or intermediate support, which may take the form of a wire spud 2|, embedded in the bead I4. The straight end terminals oi' the sections I8 and I9 are in turn connected to the inner or free ends of the supporting leads I 5 and I6, which respectively preferably lie between said coiled-coil sections and the envelope I2 and arev desirably bent so that end portions 22 and z3 point toward one another. This arrangement reduces bulb blackening. as compared with the reverse arrangement in which the spud 2| would be longer than those portions of the supporting leads on the same side of the bead I4.

A preferred embodiment of my invention involves making the coiled coils I8 and I9 about 6 mm. long, as by taking a suitable length, such as about 438 mm. of 1.21 mil tungsten filament, winding it on a primary mandrel 2.4 mils in diameter, and then Windingl the two coils so formed on asecondary mandrel 9.1 mils indi-l ameter, thereby giving a double coiled coil filament adapted for glow lamp operation when a potential of about 10 volts is applied thereto. yThe supporting portions 22 and 23 of the leads I5 and `Ifli are desirably s0 disposed with respect to one barium carbonate, one of the other alkaline earth metal carbonates, or a mixture of two or more thereof. By making the sections I8'and I9 of the filament I1 as coiled coils, a larger resistorl value, where a given size of filament is employed. may be concentrated in a given space,'ar\d the emission mixture when applied thereto is trapped therein and prevented from flaking off in service. Inasmuch as the bulk of the produced discharge occurs ,between the remote end portions of-the coils I8 and I9, it is not necessaryto coat more than about half of'each of said coils, that is. the remote end portions thereof, although it is not harmful to have the whole length of each coil coated with such emission material.

If it is intended to use the lamp as one of the fluorescent type, the bulb or envelope I2 is coated on the inside with one of the usual phosphors for producing light of the desired color; or in the near ultraviolet. The exhaust procedure and cathode treatment to remove carbon dioxide is similar to that employed in any of the hot cathode uorescentlamps. The completed lamp desirably h as an inert gaseous filling, such as argon at a pressure of about 4 mm., said gas being admixed with small amount of mercury, as by placing a small pellet of that metal 20 in the envelope. It is tipped olf as indicated at 24 and desirably has a standard miniature screw-threaded base 25 applied thereto, as by cement 26, one lead being connected to the shell 2l of the base and the other to the center contact 28 thereof.

Whensuch a lamp, suitably ballasted, is energized by alternating current Iapplied to the leads I5 and I6, the coated coils I8 and I9 are rst heated to electron emission temperature and then a discharge takes place between parts thereof near the connections with the lead portions 22 and 23. This results in the formation of a cathode glow around the coils, involving the production of a copious amount of ultraviolet radiation which, because of the mercury, involves a large proportion of such in the neighborhood of 2537 A. U. Such radiation activates the phosphor or iiuorescent coating 29, if present on the envelope I2. If it is desired to use such a lamp to generate such radiations of 2537 A. U., the envelope should be made of glass permeable thereto, such -as Corning #972, high transmission ultraviolet glass, which i-s a form of Corex glass, and the fluorescent coating omitted.

lThe lamp current passes partly through the coils and partly as the glow discharge. An increase in the total current normally increases the proportion of current that passes as the discharge and reduces the total voltage drop across the lamp. With a, lamp having coils as described, the discharge begins when the current exceeds .1

ampere. When the current rises to .'15 ampere,

the lamp glows brightly. The voltage-,drop across the lamp does not deviate much from 10 volts,

. but has a tendency to fall slightlyvwith an increase in the current.

It will be understoodthat the fluorescent ma- Y terial or phosphor may be employed on the bulb can be used to give near ultravioletfor black ligh illumination of the dials. As such a lamp produces some radio interference it is desirable to minimize this by employing a small condenser, which may be in the base of the lamp in parallel with the lament thereof.

Referring now to the embodiment f my invention illustrated inFig. 4, there is shown a mount I3 which may be used as an alternative for the mount I3 of the preceding embodiment. This mount comprisesa flare 3I from which supports 32, 33and 34 project, all of which are desirably formed of nickel. 'I'he supports 32 and 33 connect with the leads I5 and I6, as in the press 35, while the support 34 is merely a spud projecting therefrom. The filament I'I may be identical with the filament I1 of the preceding embodiment.v The flare 3| is sealed to an envelope or bulb (not shown) in the usual manner when using such a mount, rather than by the buttsealing method of the i'lrst embodiment.

Referring now to the embodiment of my invention illustrated in Fig. 5, there is shown a construction identical with that of Fig. 4 except that vthe plane of the filament IIb, instead of approximately including the lamp axis or extending lengthwise of the bulb, is generally perpendicular to the said axis. As in the preceding embodiment, however, its remote ends are connected to supports 32h and` 33h, which may be of material corresponding with supports 32 and 33. The connecting non-coiled portion between the adjacent ends of the coils I8b and I9b is desirably in order to give desired colors, as for Christmas tree decoration. Such lamps may also be used in radio receivers in series with the tubes or cathode laments thereof. In this instance the lamps united, as by spot welding, to intermediate support 34h, which may correspond generally with support 34 of the preceding embodiment, except that it is longer and has an angular projection in order to provide the desired distance between the free end portion thereof and the lamp axis. The free end portions of the supports 32b and 33", instead of being bent toward one another, like the portions 22 and 23 of the first embodiment, are desirably oset from the Vpress-enclosed portions by bending, as illustratechso that the distance between t e free end of the support 34h and each support 3 b and 33b may be approximately 9 mm. while the distance between the supports 32b and 33b may be between 2 and 5 mm.

Fig. 6 represents preferably eight lamps Il which may be used for Christmas tree illuminaity, such as iron. The magnitude of the resistor used in' such an arrangement is desirably in the neighborhood of 200 ohms, so that current after stabilization is about milliamperes.

A desirable form of ballast lamp 36 is one'con taining a tungsten lament of such proportions that when operated in series with a selected number 'of glow lamps II, its larnent gives off some light so that it may function as one of the lamps in the series. Its envelope may be coated with a pigment of the desired character, like an ordinary Christmas tree lamp if the others of the series are to be used for that purpose, the envelope being uniform in size and shape as compared with those of the other lamps. The ballast lamp, therefore, may be readily and desirably formed as an incandescent lamp, having accating applied either to the outside. as distinguished from the inside, or a darker color than the fluorescent material on the other lamps, whereby it may easily be identified.

Fig. 7 shows a lamp I I embodying my invention,

and/or glow lamp, particularly adapted for decorative purposes, which has the'following advantages over the customary type of lament lamps for series operation:

1. Low power consumption. 2. Cooler operation. 3. Colors not obtainable by pigment filters. 4. Readily identified in case of burn-out.

Ordinarily when a. filament lamp in series fails, all the lamps' in the series go out and it is timeconsuming to identify the burn-out. lamp embodying my invention fails, it is ordinarily through loss of emission material so that the failure isvmerely in the formation of the glow. When this occurs enough current passes through the filament to permit the remaining lamps in the series circuit to continue operation; Hence dev fective or worn out lamps can be easily identified.

5. Longer life.

It will be understood that the same, or a dif- The lamp I I may serve to furnish v- When a electron-emission material thereon, an enclosing envelope and an inert gaseous filling in said envelope, whereby when a suitable potential is impressed4 at the ends of said filament, first passage of current along with heating to electron emission temperature and then a glow discharge oc` curs between only the remote end portions thereof in addition to the passage of the current along said filament.

2. A negative-glow lamp of the gaseous-conduction type comprising a pair of coils of tungsten filament, an intermediate support to which adjacent joined ends of said coils are connected, an enclosing envelope. interior supporting leads extending beyond said support and vto which the remote ends of said coils are connected and spaced a short distance apart so as to form a narrow V, electron-emission material on said coils, and an inert gaseous filling admixed with mercury v'apor in said envelope, whereby when 'a suitable potential is impressed at the remote ends of said coils, the latter first pass current therealong and heat to electron'- emitting temperature, and then a glow discharge occurs between the supporting-lead-connected portions of said coils in addition to the passage of the current along saidfilament.

3. A negative-glow lamp of' the gaseous-conduction type comprising a iilament in two sections extending at a small angle to one another, the free ends of said sections being spaced a small distance, such as between two and five millimeters, electron-emission material on said filament sections, an enclosing envelope, and an 4Q inert gaseous filling admixed with mercury vapor ferent form of envelope or bulb may be used for enclosing the mounts of the `embodiments of Figs. 4 and 5 as is used for that of Fig. 3. It will also be understood that I may use a different form of bulb for enclosing the mount of the embodiment of' Fig. 2, although the shape illustrated is believed preferable for that type of mount. For the type of mount illustrated in Fig. 5 a spherical bulb or one not as long as that of Fig. 2 may be preferable.

When it is desired to take the light mainly from the side, or perpendicular to the aXis of the lamp orbase thereof, the form of mount illustrated in Figs. 3 and 4, is believed. to be preferred.` 'However, when the light is taken'mainly from the end,

or axially. of the lamp, the form of mount ofy Fig. 5 is believed to be more desirable. It will be understood that in any form, the dumet, or other lead-in conductor, may be continued to form internal supporting leads or may be joined, preferably in the press, with nickel or other internal supporting portions.

While the angle between the coils may be varied, a small angle, or one in which theremote ends of the coils are spaced a relatively short distance, appears to be the more desirable, as making a lamp which is more efficient than one in which the coils are disposed at a large angle t0 one another. It will also be understood that although I have disclosed a preferred embodiment of my filament, yet I do not wish to be limited thereto as other forms may be satisfactorily employed.

Although preferred embodiments of my invention have been disclosed, it will be understood in said envelope, whereby when a suitable potential is impressed fat the ends of said filament, the latter is heated to electron-emitting temperature by the fiow of current along the filament-and a glow discharge occurs between the remote end portions thereof in addition to the passage of the current along said filament.

4. A negative-glow lamp of the gaseous-conduction type comprising 4a pair of coils of tungsten filament joined at adjacent ends and there connected to an intermediate support, an enclosing envelope, interior supporting leads which extend'beyond said support and have inwardly bent end portions to which the remote ends of said coils areconnected and spaced a short distance apart, so as to lie at a small angle with respect to one another, each of said coils being coated with alkaline earth emission material, and an inert gaseous filling admixed with mercury vapor in said envelope, whereby when a suitable potential is impressed at the remote ends of said coils a glow discharge occurs therebetween in addition to the passage of the current along said filament.

5. A negative-glow lamp of the gaseous-conduction type comprising a V shaped filament, electron-emission material thereon, an enclosing envelope the inner surface of which is coated with fiuorescent material, and an inert gaseous filling admixed with mercury vapor in said envelope, whereby when a suitable potential is impressed upon said filament, a glow discharge occurs between portions thereof in addition to the passage of thecurrentalong said filament and the fluorescent material is activated.

6. A negative-glow lamp of the gaseous-conduction type comprising a pair of coils of tungsten filament, adjacent ends of which are joined and connected to an intermediate support, an enclosing envelope, interior supporting` leads to which the remote ends of said coils are connected in order to space them a short distance apart so that they make a Ynarrow angle.

with respect to one another, each lead lying between the coil to which connected and the adjacent wall portion of said envelope to reduce blackening, electron-emission material on said coils, and an argon filling admixed with mercury vapor and at a pressure of about four millimeters in Said envelope, whereby when a suitable potential'is impressed on said coils they heat to electron-emitting temperature and a glow discharge occurs between portions thereof in addition to emission material, remote ends of said coils being connected to the free ends of said supporting leads therebeyond, and the connected adjacent ends of which are fastened to said spud therebetween, holding said filament with the coils making a small' angle therebetween, and argon admixed with mercury vapor contained in said envelope so that a glow discharge develops during normal operation inv addition to the passage of the current along said lament.

8. An ultraviolet radiations generator comprising a, negative-glow lamp of the gaseous-conduction type having a V shaped filamyent, each side of said V comprising a coiled-coil, electronemission material trapped in the meshes of said coils, an enclosing envelope of ultraviolet transmitting material and an inert gaseous filling admixed with mercury vapor in said envelope, whereby when a suitablepotential is impressed at the ends of said filament, iirst heating to electron emission temperature and then a glow discharge and generation of ultraviolet radiationsv terial, and an inert gaseous filling admixed with mercury vapor in said envelope, whereby when a suitable potential isimpressed at the ends of said filament a glow discharge occurs between remote end portions thereof in addition to current passing along the entire filament, an incandescent decorative lamp in series with all of said glow lamps and comprising a filament in an envelope uniform in size and shape with those of said glow lamps, whereby it serves as a ballast for said glow lamps when the whole series is energized from a source cf potential, while appearing to be the same as one of the series.

10. In combination, a radio receiving set 'involving a plurality of receiving tubes containing cathode-heating filaments, a negative-glow lamp of the gaseous-conduction type comprising a V shaped filament, electron-emission material thereon, an enclosing envelope, and an inert gaseous filling admixed with mercury vapor in said envelope, in series with a plurality of said cathode heating filaments. whereby the latter serve as ballast for said negative-glow lamp, and the glow lamp may serve for illuminating a desired portion of the receiving set.

1l. A negative glow lamp of the gaseous conduction type having an incandescible filament comprising about 438 millimeters of 1.21 mil tungsten'wire, wound as a pair of coils connected by an uncoiled section, each coil being about 6 millimeters long and formed by winding about a 2.4 mil primary mandrel and then wound about a 9.1 mil secondary mandrel, the remote portions of said coils having trapped therein an alkaline earth electron-,emission mixture, said coils diverging from the uncoiled connection at an acute angle, so that the remote coil ends are spaced from 2 to 5 millimeters, an enclosing envelope, interiorsupporti'ng leads extending from a glass element in said envelope, lying alongside said coils, disposed between the same and said envelope, and formed with end portions' inturned and connected to the remote ends of said coils, an interior intermediate support extending from said glass element in the same general direction as the supporting leads, connected to the uncoiled connecting section of said filament, and

holding it closer to said glass element than the remote ends of said coils, and an argon lling in said envelope at a pressure cf about 4 millimeters, whereby when a potential of about l0 volts is impressed on said coils in series, they pass current, heat .to electron-emitting temperature, and a glow discharge occurs between the portions thereof which carry the electron-emission material in addition to the passage of the current along said filament.

CHALMERS MOREHEAD. 

